24 Questions
Where does the process of glycolysis occur?
Cytoplasm
What happens to the carbon atoms during glycolysis?
They are split into two molecules of pyruvate
What is the energy yield of glycolysis?
2 ATP
What is the purpose of the energy-investment phase of glycolysis?
To invest energy in the form of ATP to facilitate the breakdown of glucose
How is glycolysis regulated?
By feedback inhibition
What is the result of high levels of ATP binding to the regulatory site of phosphofructokinase?
The enzyme is inhibited
What is the condition required for re-oxidation of FADH2?
Aerobic conditions
What is the significance of the fourth step of glycolysis?
It divides the glucose molecule into two pieces
Which stage of cellular respiration can function anaerobically?
Glycolysis
What is the role of CoA in the citric acid cycle?
To drive an oxidation and a reduction step forward
Why is it necessary for ATP to bind to the active site of phosphofructokinase?
To activate the enzyme
What is the net production of ATP per glucose molecule in the reactions so far?
2 ATP
Where is most of the energy stored at this point?
NADH and FADH2
Where is the electron transport chain located in the mitochondrion?
Inner mitochondrial membrane
What happens to the electrons as they pass through the electron transport chain?
They decrease in free energy
What is the result of electron transfer in the electron transport chain?
Protons are pumped into the intermembrane space
What is the net ATP yield of glycolysis?
2 ATP
What is required to keep glycolysis running?
Glucose
In anaerobic respiration, what is the terminal electron acceptor?
Sulfate
What is the primary mechanism of ATP production in fermentation?
Substrate-level phosphorylation
What is the flow of energy during cellular respiration?
Glycolysis → Electron transport chain → ATP synthesis
What is the purpose of the proton-motive force in the electron transport chain?
To generate ATP
What is the role of ATP synthase in the electron transport chain?
To use the proton-motive force to drive ATP synthesis
What is the process by which energy from a proton-motive force is used to drive ATP synthesis?
Chemiosmosis
Study Notes
Cellular Respiration
- In the absence of oxygen, NADH can be re-oxidized, but FADH2 can only be re-oxidized when oxygen is available.
- Glycolysis is the only stage of cellular respiration that can function anaerobically.
- CoA is used in two steps of the citric acid cycle, acting as an agent to drive the reactions forward.
Oxidative Phosphorylation: Electron Transport Chain and Chemiosmosis
- Electrons are transferred from NADH or FADH2 to the electron transport chain.
- The electron transport chain is located in the inner mitochondrial membrane.
- Electrons are passed through a series of proteins to oxygen, ultimately forming H2O.
- The electron transport chain generates no ATP, but breaks the large free-energy drop from food to O2 into smaller steps.
- Electron transfer in the electron transport chain causes proteins to pump H+ ions from the mitochondrial matrix to the intermembrane space, creating a proton-motive force.
- The energy stored in the H+ gradient is used to drive ATP synthesis through chemiosmosis.
- ATP synthase uses the exergonic flow of H+ ions to drive ATP synthesis.
Chemiosmosis
- Chemiosmosis is the use of energy in a H+ gradient to drive cellular work.
- In oxidative phosphorylation, the energy from the electron transport chain is used to pump H+ ions across the membrane, creating a proton-motive force.
- This force is then used to drive ATP synthesis through ATP synthase.
Fermentation and Anaerobic Respiration
- Glycolysis can produce ATP with or without oxygen, but most cellular respiration requires oxygen to produce ATP.
- In the absence of oxygen, glycolysis couples with fermentation or anaerobic respiration to produce ATP.
- Anaerobic respiration uses an electron transport chain with an acceptor other than O2, such as sulfate.
- Fermentation uses substrate-level phosphorylation to generate ATP.
Citric Acid Cycle and Oxidative Phosphorylation
- The citric acid cycle completes the breakdown of glucose.
- Oxidative phosphorylation accounts for most of the ATP synthesis.
Glycolysis
- Glycolysis breaks down glucose into two molecules of pyruvate.
- Glycolysis occurs in the cytoplasm and has three major phases: energy-investment, cleavage, and energy-payoff.
- Two ATP are used at the beginning of glycolysis to phosphorylate the glucose.
- Glycolysis is regulated by feedback inhibition.
- High levels of ATP inhibit the third enzyme, phosphofructokinase.
- Phosphofructokinase has two binding sites for ATP: one active site and one regulatory site.
- The fourth step of glycolysis is the aldolase step, where the molecule is broken into two pieces.
Understanding the citric acid cycle and its relation to cellular respiration, including the roles of NADH, FADH2, and CoA. Quiz covers the stages of cellular respiration and the conditions required for certain reactions to occur.
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